Fan impeller with integrated precipitation of fat particles in particular for a cooking device

ABSTRACT

The disclosure relates to a fan impeller including a base plate and a plurality of fan impeller blades fixed to the plate. The fan impeller blades are positioned in an essentially vertical manner on the base plate and have a substantially radial arrangement, each fan impeller blade including a front edge facing radially outwardly that is substantially perpendicular to the base plate, a rear edge facing radially inwardly that is substantially perpendicular to the base plate, an exterior surface located on the delivery side of the fan impeller and an interior surface located on the intake side of the fan impeller. At least one raised element is mounted and/or configured on the exterior surface of at least one selection of the fan impeller blades, the element being positioned at a distance from the base plate and extending substantially in a diagonal manner away from the base plate from the front edge to the rear edge of the fan impeller blades. The disclosure also relates to a fan impeller in a cooking device and to a cooking device including at least one inventive fan impeller.

The present invention concerns a fan impeller with a base plate and anumber of fan impeller blades fastened to the base plate, the fanimpeller blades being essentially arranged perpendicular to the baseplate and forming an essentially radial arrangement in which each fanimpeller blade has a front edge arranged radially outward andessentially perpendicular to the base plate, a rear edge arrangedradially inward and essentially perpendicular to the base plate, anouter surface arranged on the delivery side of the fan impeller and anouter surface arranged on the intake side of the fan impeller.

Fan impellers are generally known from the prior art and are used tocirculate air. Fan impellers are known in a wide variety of forms, forexample, fan impellers with propeller-like blades or with blade-likevanes are known. One problem in fan impellers known from the prior artis that solid and/or liquid particles present in the circulated air candeposit on the vanes of the fan impeller, which leads to soiling of thefan impeller. Undesired distribution of solid and/or liquid particlescan also occur from the known fan impellers.

A particular problem is circulation of solid and/or liquid particles,especially in the form of grease particles, when the fan impeller isarranged within a cooking appliance. The fan impeller is generallyarranged in a cooking appliance in a fan compartment separated from thecooking space by an air baffle, draws in air from the cooking space anddiverts it radially to the enclosing walls in order to create air flowwithin the cooking appliance from the cooking space into the fancompartment and back again to the cooking space. A heating device oralso a heat exchanger is often arranged around the fan impeller so thatcirculated air is also guided past this heating device or this heatexchanger in order to be heated. During a cooking process greaseparticles present in the circulated air can then also be guided to theheating device, where they can be burned, which can lead to a reductionin food quality and an odor burden. This is a particular problem if theair is permanently circulated within the cooking appliance by the fanimpeller, in which case the solid and/or liquid particles arecontinuously kept in the gas volume by the circulating flow.

In order to reduce depositing of solid and/or liquid particlescirculated by the fan impeller within a cooking appliance, is a deviceis known from DE 42 06 846 C2 that includes an impact surface or aseparation ring around the fan impeller on which a gas flow prevailingin the gas volume occurs, in which case the solid and/or liquidparticles are at least partially separated on impact and can go to afirst bypass area.

A fan impeller with a number of radially arranged blades that protrudeessentially parallel to the axis of rotation of the fan impeller from asupport plate or base plate facing the housing wall of the cookingappliance is also known from DE 43 074 05 C2 in which baffles arearranged at least between some of the blades near the support disk, butwith a spacing from it, whose radial outside edges are essentially flushwith the outside periphery of the fan impeller, the radial inner edgeslie at a spacing from the axis of rotation of the fan impeller and forma nozzle device with the support disk and the two adjacent blades tocreate a gas stream near the support plate directed radially outward.

A fan impeller is known from U.S. Pat. No. 1,688,345 in which at leastone elevation extending away from the base plate is arranged on theouter surface of at least one part of the fan blades.

However, a shortcoming in the devices known from the prior art is thatthe efficiency of the fan impeller is reduced by the additional devicessurrounding the fan impeller or arranged in the fan impeller, since theadditional devices represent an obstacle to flow for the circulated air.

The task of the present invention is therefore to modify a generic fanimpeller so that the drawbacks of the prior art are overcome. Inparticular, it is to be prevented that solid and/or liquid particlespresent in air circulated in a cooking appliance directly reach aheating device or heat exchanger surrounding the fan impeller because ofthe fan impeller without significantly reducing the efficiency of thefan impeller.

The task of the present invention is solved in that at least oneelevation is arranged and/or formed on the outer surface of at least onepart of the fan impeller blades, which is spaced from the base plate andextends away from the base plate essentially diagonally from the frontedge to the rear edge of the fan impeller blades.

It is then prescribed in particular that the elevation be designed inthe form of a step on and/or in the outer surface.

The invention also proposes that the fan impeller blades be curved sothat the outer surface curves radially outward between the front edgeand the rear edge.

It is advantageous that at least one elevation has a height of about 1to 10 mm, preferably 2 to 4 mm, at least in areas.

It can also be prescribed according to the invention that at least oneelevation has a width from 1 to 10 mm, preferably 2 to 4 mm, at least inareas.

The fan impeller according to the invention is preferably characterizedby the fact that the spacing of at least one elevation to the baseplate, at least in areas, especially in the region of the front edge, isat least 5 to 25 mm, preferably 10 to 20 mm.

A support element as in the form of a cover ring, of the fan impellerblades on the side of the fan impeller blades opposite the base plate isalso proposed with the invention.

It is preferred according to the invention that at least one elevationbe designed arc-like at least in areas, in which it is preferably bentfrom the corresponding rear edge to the corresponding front edge awayfrom the support element.

It is also proposed that at least one elevation forms an angle of 45° to90° with the front edge, preferably an angle of 70° to 90°.

It is preferred that at least one elevation has at least in areas aspacing to the support element, especially in the region of the rearedge, of at least about 1 to 10 mm, preferably 5 to 15 mm.

It is also preferred that at least one elevation be formed by at leastone wire.

It is also proposed with the invention that at least one elevation bewelded, at least in areas onto the outer surface of the fan impellerblade.

It can be proposed in particular according to the invention that on theoutside surface of at least one fan impeller blade, preferably each fanimpeller blade, a distinct edge as in the form of a groove, be formed inthe fastening region between the corresponding elevation and the outersurface, at least in areas, on the side lying in the direction ofrotation of the fan impeller.

It is advantageously prescribed that at least one elevation have aprofiled cross-section at least in areas, be preferably bulged, in whichthe focal point of the bulge lies on the side of the elevation facingthe rear edge, and/or has at least one groove, preferably on the sidefacing the rear edge.

It is also preferred that at least one elevation be tightly joinedpreferably with silicon to the outer surface, at least in areas, on theside facing away from the direction of rotation of the fan impeller.

The fan impeller according to the invention can be arranged in a cookingappliance.

The basis of the present invention is the surprising finding that byelevations on the outer surface of the fan impeller blades on a baseplate, a situation in which solid and/or liquid particles contained inthe circulated air, especially in the form of grease particles, arediverted radially by the fan impeller is avoided. Instead, solid and/orliquid particles that strike the outer surfaces of the fan impellerblades are stopped on the elevation and diverted in the direction towardthe base plate by the special geometry of the elevation. In the regionof the base plate the solid and/or liquid particles can then be releasedfrom the fan impeller blades without striking devices that are arrangedradially around the fan impeller, for example, a heating device within acooking appliance.

Since the solid and/or liquid particles are not released by the fanimpeller blades directly to the devices radially surrounding the fanimpeller, like a heating device, a situation is prevented in whichgrease particles in particular can be burned on the heating device,which could lead to a reduction in food quality and an odor burden.

On the other hand, because of the fan impeller according to theinvention, a situation is surprisingly achieved in which the efficiencyof the fan impeller is not significantly compromised, since no largeobstacles are arranged in the radial flow path of the circulated air. Inaddition, the elevations arranged on the outsides of the fan impellerblades ensure additional stability of the fan impeller bladesthemselves.

Additional features and advantages of the invention are apparent fromthe following description, in which a practical example of the inventionis described in detail by means of a drawing consisting of a singleFIGURE. The FIGURE shows a perspective view of a fan impeller accordingto the invention.

The FIGURE shows a perspective view of a fan impeller 1 according to theinvention that can be incorporated in a fan compartment of a partiallydepicted cooking appliance in order to circulate air rotating in thedirection of arrow A in a cooking space that is separated in areas fromthe fan compartment by an air baffle (not shown). The fan impeller 1 hasa base plate 2, on which a number of fan impeller blades 3 are arranged,which face the cooking space of the cooking appliance. The fan impellerblades 3 are curved and arranged essentially perpendicular to the baseplate 2 in order to form an essentially radial arrangement on base plate2. Each fan impeller blade 3 during operation has a rear edge 5 thatcomes in contact first with the circulating air and an outer surface 6arranged on the delivery side fan impeller 1 during operation. Anelevation 7 is also provided on the outer surface 6 of a fan impellerblade 3, which extends away from base plate 2 essentially diagonallyfrom one front edge 4 to rear edge 5 of the fan impeller blade 3. Theelevation 7 is then arranged with a spacing from 10 to 20 mm from baseplate 2 on the outer surface 6. The elevation 7 can extend completelyover the entire width of fan impeller blade 3 or have a spacing to theside of the fan impeller blade 3 opposite base plate 2, in which thespacing is preferably 5 to 15 mm. On the side of fan impeller blade 1opposite base plate 2 a cover ring 8 is provided, which ensuresadditional stabilization of the fan impeller blades 3 within the fanimpeller 1. The elevation 7 should rise from the outer surface 6 of thefan impeller blade 3 by 2 to 5 mm and end with a sharp edge on the rearedge 5 of fan impeller blade 3 on the end facing the air flow in orderto form a discharge groove for solid and/or liquid particles, whichprevents further flow of the solid and/or liquid particles beyondelevation 7 and guides them in the direction of base plate 2. Inaddition, sealing can be provided on the side lying in the flow shadowbetween the outer surface 6 and elevation 7.

This sealing can occur, for example, with silicone, but any othersealing can be provided that is obvious to one skilled in the art inthis field.

The method of operation of the impeller blade 1 according to theinvention is described below.

The impeller blade 1 is rotated in the fan compartment in the directionof arrow A via a motor not shown in the FIGURE, and therefore draws inair from the cooking space through a center opening in the air baffleand guides it radially outward so that it goes back to the cooking spacefrom the fan compartment via the air baffles. Solid and/or liquidparticles, especially grease particles of different size, that reach theregion of fan impeller 1, strike the outer surfaces 6 of fan impellerblades 3 on the delivery side of the fan impeller and are diverted alongelevation 7 in the direction toward base plate 2. If the solid and/orliquid particles reach the end region of elevation 7 on the front edge 4of fan impeller blades 3 (and finally the base plate 2), the solidand/or liquid particles released at that point cannot be releaseddirectly to the device radially surrounding the fan impeller 1, forexample, in the form of a heating device (not shown) or a heat exchanger(not shown). Because of this “leading” of the solid and/or liquidparticles past a heating device and/or a heat exchanger, their burningis prevented, which can lead to an odor burden and a negative effect onthe cooking result. Instead, the separated solid and/or liquid particlescan be disposed of

The fan impeller according to the invention in a cooking appliancetherefore prevents solid and/or liquid particles from being depositeddirectly on a heating device enclosing the fan impeller and also ensuresthat air circulated by the fan impeller 1 can be diverted completelyradially, since the efficiency of the fan impeller 1 is only slightlyreduced by the elevation 7. The fan impeller 1 acquires higher stabilitybecause of the elevations 7. LIST OF REFERENCE NUMBERS

-   1 Fan impeller-   2 Base plate-   3 Fan impeller blade-   4 Front edge-   5 Rear edge-   6 Outer surface-   7 Elevation-   8 Cover ring-   A Direction of rotation

1. Fan impeller having an intake side and a delivery side and comprisinga base plate and a plurality of fan impeller blades fastened to the baseplate, the fan impeller blades being disposed substantiallyperpendicularly to the base plate and forming a substantially radialarrangement, in which each fan impeller blade has a front edge disposedradially outwardly and substantially perpendicular to the base plate, arear edge disposed radially inwardly and substantially perpendicular tothe base plate, an outer surface disposed on the delivery side of thefan impeller and an inner surface disposed on the intake side of the fanimpeller wherein at least one elevation is at least one of disposed orformed on the outer surface of at least one part of the fan impellerblades and is spaced from the base plate and extending away from thebase plate substantially diagonally from the front edge to the rear edgeof the fan impeller blades.
 2. Fan impeller according to claim 1,wherein the elevation comprises a step on and/or in the outer surface.3. Fan impeller according to claim 1, wherein the fan impeller bladesare curved so that the outer surface curves radially outwardly betweenthe front edge and rear edge.
 4. Fan impeller according to claim 1,wherein at least one elevation has a height of about 1 mm to 10 mm, atleast in a portion of the elevation.
 5. Fan impeller according to claim1, wherein at least one elevation has a width of 1 mm to 10 mm, at leastin a portion of the elevation.
 6. Fan impeller according to claim 1,wherein a spacing of at least one elevation to its associated base plateis about 5 mm to 25 mm, at least in a portion of the elevation.
 7. Fanimpeller according to claim 1, comprising a support element, of the fanimpeller blades, on a side of the fan impeller blades opposite the baseplate.
 8. Fan impeller according to claim 7, comprising at least oneelevation that is at least partially arc-shaped.
 9. Fan impelleraccording to claim 1, wherein at least one elevation forms an angle of45° to 90° with the front edge.
 10. Fan impeller according to claim 7,wherein at least one elevation has at least in areas a spacing to asupport element of at least about 1 mm to 10 mm.
 11. Fan impelleraccording to claim 1, wherein at least one elevation is formed by atleast one wire.
 12. Fan impeller according to claim 1, wherein at leastone elevation is welded onto the outer surface of the fan impellerblade, at least in a portion of the elevation.
 13. Fan impelleraccording to claim 1, further comprising a distinct edge formed on theouter surface of at least one fan impeller blade.
 14. Fan impelleraccording to claim 1, wherein at least one elevation has a profiledcross-section at least in a portion of the elevation.
 15. Fan impelleraccording to claim 1, wherein that at least one elevation is tightlyjoined, to the outer surface, at least in areas, on the side facing awayfrom the direction of rotation of fan impeller.
 16. A cooking appliancecomprising a fan impeller according to claim
 1. 17. Fan impelleraccording to claim 4, wherein at least one elevation has a height of 2mm to 4 mm, at least in a portion of the elevation.
 18. Fan impelleraccording to claim 5, wherein at least one elevation has a width of 2 mmto 4 mm, at least in a portion of the elevation.
 19. Fan impelleraccording to claim 6, wherein said spacing is in the area of the frontedge.
 20. Fan impeller according to claim 6, wherein said spacing is 10mm to 20 mm, at least in a portion of the elevation.
 21. Fan impelleraccording to claim 8, wherein said elevation is bent from thecorresponding rear edge to the corresponding front edge away from thesupport element.
 22. Fan impeller according to claim 9, wherein saidangle is 70° to 90°.
 23. Fan impeller according to claim 10, whereinsaid spacing is in the region of the rear edge.
 24. Fan impelleraccording to claim 10, wherein said spacing is 5 mm to 15 mm.
 25. Fanimpeller according to claim 13, wherein said distinct edge is found inthe fastening region between the corresponding elevation and the outersurface at least in areas on the side lying in the direction of rotationof the fan impeller.
 26. Fan impeller according to claim 13, whereinsaid distinct edge is formed or disposed on each fan impeller blade. 27.Fan impeller according to claim 14, wherein said elevation having aprofiled cross-section is bulged, at least in a portion of theelevation.
 28. Fan impeller according to claim 27, wherein said elementhas at least one groove.
 29. Fan impeller according to claim 15, whereinsaid element is tightly joined to the outer surface with silicone. 30.Fan impeller according to claim 7, wherein the support element forms acover ring.
 31. Fan impeller according to claim 13, wherein saiddistinct edge has the form of a groove.
 32. Fan impeller according toclaim 27, wherein a focal point of the bulge lies on the side of theelevation facing the rear edge.
 33. Fan impeller according to claim 28,wherein said groove is on the side facing the rear edge.